Composting made simple

If you're a gardening newbie, you've no doubt wondered about the mysteries of compost, a substance about which veteran tenders-of-the-soil tend to wax rhapsodic.

Dedicated composters have their secret formulas for achieving large amounts of this desirable stuff. They mix "greens" and "browns" according to strict formulas. They aerate, tumble, pitch and dampen, cover and uncover, all to get their precious pile to heat up and rot briskly. They are people with a mission.

Truth is, you don't have to be a compost hobbyist to benefit from having a heap. It gives you something to do with yard waste you can't easily throw away -- and you wind up with a useful end product that does wonderful things for your soil.

You don't have to start out big or worry about stoking a "hot" pile that will produce compost in five to 15 weeks. You can take the laissez-faire route, make a "cold" pile, and have equally useable compost in a year or so.

You don't need a $400 deluxe composter, either. We've got four plans for cheap and easy homemade bins that anyone can whip up in an afternoon (see graphic). The point of a bin is to neatly corral your raw materials in a concentrated pile of sufficient size to get decomposition working for you.

A certain critical mass is required to set the process in motion, generally a minimum of one cubic yard, or a pile three feet in every dimension. The stuff needs to be damp to rot, so you'll want to locate your bin where wetting it down occasionally is not big chore.

You can't go too far wrong if you keep the fundamentals in mind: Air + water + fuel = a happy home for the microbial life that digests your junk, turning it into compost.

Composting microbes are aerobic, not in the sense of needing a pulse-pounding workout, but in the sense that they can't survive without air. If your pile is a compacted mass rather than a reasonably fluffy heap, the aerobic good guys die off and the anaerobic bad guys take over, making a stink.

Moisture is another essential ingredient but that doesn't mean the pile should be sopping wet. The ideal consistency is "as wet as a wrung-out sponge." You may have to hose down the heap in very dry weather or add water to a closed bin (like the garbage can composter) that rain water can't penetrate.

Fuel is simply the raw material you want to convert to compost. There are two basic kinds: the carbon-rich "browns," including dry, dead things like straw, autumn leaves and sawdust, and the nitrogen-rich "greens," meaning fresh, wet material like fruit and vegetable scraps, green leaves and manure.

You'll know your compost is ready to use when the separate components can no longer be identified but have become a dark, crumbly, undifferentiated material. Compost is not fertilizer, being low in essential plant nutrients, but it teems with beneficial bacteria, fungi and microscopic organisms that boost soil health.

What do you do with it? Dig it into substandard soil to improve the structure. "Top dress" by spreading a few handfuls around plants you want to encourage. Add it to potting soil when you're filling patio containers. Make "compost tea" by soaking it in water, and use the drained liquid to water seedlings.

What not to compost (and why):
Scraps and sawdust from chemically treated wood, which could include toxic compounds.
Diseased plants, which might infect desirable plants.
Human wastes, which contain pathogens and heavy metals.
Meat, cheese and bones, which are attractive to critters.
Fatty foods, oil and grease, which prevent breakdown of materials they coat.
Cat, dog or other pet waste, which can carry diseases and parasites.
Pernicious weeds, which may resprout from seeds or roots.
Charcoal briquettes (or their ashes), which do not break down.
Garden chemicals (pesticides, herbicides, cleaners), which will poison compost.
Synthetic items (plastic, glass, landscape fabrics), which don't decompose.